DC Link Ground Fault Isolation via Sequential Converter Activation
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Solution Overview
Problem
Existing power systems face challenges in accurately detecting, isolating, and remedying ground faults, particularly in complex electrical circuits, which can lead to system damage or failure, and current solutions are often expensive and inefficient.
Innovation Solution
A ground fault detection system that includes a control unit connected to a power system with a DC link, battery bank, link capacitor unit, and power converters, which disconnects the battery bank upon fault detection and sequentially activates power converters individually using capacitor power to isolate the fault, distinguishing between DC and AC ground faults based on voltage signal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ground fault detection is implemented in complex electrical circuits, then ground fault detection capability is improved, but system cost increases and implementation difficulty increases
Solution Approach 1:
The system segments the power conversion system into modular units (power conversion modules) that can be individually tested. Each module can be isolated and evaluated separately through sequential activation, making ground fault detection manageable in complex systems with multiple converters and battery banks.
Solution Approach 2:
The control unit performs preliminary ground fault detection by monitoring voltage signals before full system operation. The system proactively identifies ground faults through continuous voltage monitoring and threshold comparison, enabling early detection before faults propagate through the complex circuit.
2Reliability
If ground fault detection is implemented in complex electrical circuits, then ground fault detection capability is improved, but implementation difficulty increases
Solution Approach 1:
The system divides the complex electrical circuit into discrete testable segments (individual power conversion modules). By activating modules sequentially rather than simultaneously, the system can isolate ground faults to specific modules, making detection and measurement straightforward even in complex configurations.
Solution Approach 2:
The system dynamically adjusts its testing approach by sequentially activating power conversion modules based on detected ground faults. The control unit adaptively determines which modules to test next based on real-time voltage signal analysis, simplifying the detection process for complex circuits.
3Reliability
If ground fault detection system is implemented, then ground fault remediation is improved, but system cost increases
Solution Approach 1:
The control unit performs ground fault detection and module identification autonomously without requiring external testing equipment or complex additional hardware. The system uses its existing voltage monitoring capabilities and sequential activation functions to self-diagnose ground faults, reducing the need for expensive external detection systems.
Solution Approach 2:
The control unit serves multiple functions: it controls power conversion module operation, monitors system voltage, detects ground faults, and identifies faulty modules. This multi-functionality eliminates the need for separate dedicated ground fault detection hardware, reducing overall system cost while maintaining detection capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid and accurate identification and isolation of ground faults without exposing the battery bank to damaging voltages, preventing system damage and allowing for quick recovery.
Implementation Method 1
a link capacitor unit (e.g., one or more capacitors) connected to the DC link
Data Source
AI summary
A ground fault detection system for a power system having a DC link, a battery bank, a link capacitor unit connected to the DC link, and plural power converters connected to the DC link. The power converters convert first DC power from the DC link to at least one of AC power or second DC power for powering at least one electrical load. A control unit disconnects the battery bank from the DC link responsive to detection of a ground fault, to deactivate operation of the power converters, and to sequentially at least partially activate, with power from the link capacitor unit, each of the power converters individually until a sensed voltage signal of the DC link is indicative of the ground fault being associated with one of the power converters.